There is some confusion here.
The data model does NOT have a Many to Many between Classes and Instructors. The modeler has resolved this but means of the junction table,
Instructors_Classes. This table shows/records which Instructors teach which Classes. There are no duplicates in this table. The table records the combination of Instructor_Id and Class_Id.
Code:
I'm actually already using a junction table to get the many to many relationship, but I believe it's the junction table that's creating my duplicate form issue.
No, the junction table does NOT allow you to get the many to many. The junction table is the technique to avoid/remove/reconcile the many to many by making two 1:M relations.
Code:
I'm not sure about ridding the junction table of duplicates because since I need to have duplicate CourseIDs with unique ContactIDs.
This does not make sense to me. Perhaps it's your wording, but perhaps you could define Contact, so things are more clear.